Voids/Cavities:

The gravity method, using the CG-5 Autograv Gravity Meter is very good at detecting even the smallest of voids close to surface. The resistivity imaging method, using the SARIS Resistivity Imaging System can also help.

Buried objects:

Depending on the type of buried object, many geophysical methods can be used. Methods such as the magnetic method, using the ENVI Pro Magnetometer or the SM-5 NAVMAG Cesium Magnetometer, the resistivity imaging method using the SARIS Resistivity Imaging System or even the gravity method, using the CG-5 Autograv Gravity Meter can help.

UXO:

UXO or unexploded ordnance is most easily detected with the high-precision magnetic method using the NAVMAG Cesium Magnetometer.